Some Curious Tube-builders. 



ward-directed petal-like discs are expanded, and a wreath 

 of cilia in active motion is seen to fringe them. Below 

 the large petal lobes there is a projecting angular chin, 

 which is also clothed with cilia ; and immediately below 

 this is the little organ with which Melicerta forms the 

 bricks or pellets to build its house. This apparatus 

 appears to form a small hemispherical cup, and is capable 

 of being projected forward on its short stalk. Now the 

 little Brick-maker forms the pellets for its house out of 

 the excess of food particles which float in the surround- 

 ing water, and which are brought within its reach by 

 the currents set up by the vibrating wreaths of cilia. 

 These particles can be seen whirling round the petal- 

 like lobes caught in the current of the waving cilia, 

 and are carried down to minute channels on either 

 side of the projecting chin through which they pass 

 into the cilia-clad glandular cup, which is really mix- 

 ing-chamber and mould in one. Here the particles, 

 as they revolve, are cemented together into a pellet 

 or brick ; and when the operation is completed, Meli- 

 certa bends its head forward, and the moulded brick 

 passes from the cup in which it was formed on to 

 the rim of the tower. In this fashion, brick after 

 brick is " well and truly laid " in position, and so 

 the little tower increases in height. It is quite pos- 

 sible to keep Melicerta in a healthy, active condition 

 for some time in a small trough, and by supplying 

 the little Rotifer with plant-food particles (which must 

 be very finely ground and only a very small quantity 

 given) of different colours, or with particles of car- 

 mine, to induce it to build a tube of various bands 

 of colour. 



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